SAE or Metric????

[RickyGee]

I've been researching for months in preparation to replace the PDS bearings on my 1991 500B/DP-C drives (PN 872206). I'll have limited time once I get the boat dry, so I'm planning all the tools and parts to have on hand. I'm seeing in various threads that the drives use SAE threads in some locations and Metric in others. Is that true? I thought the whole drive was metric while the Chevy engine is SAE. I'm tooling up to pull the hinge pins, double bearing box, helmet plug and to adapt my pressure test equipment, and now I'm thoroughly confused.... I've read both SAE and Metric thread callouts in all 4 locations. I may need a barley pop soon...

Thanks in advance for any sage advice.

 

[gm280]

Re: SAE or Metric????

Not knowing what you are dealing with, lots of times when we think they used both SAE and Metric on the same engine or whatever, it is because a lot of metric sizes are so close to SAE sizes that we get away with using SAE wrenches and then come across a size that the SAE just does work on and we grab the metric wrenches. So if you fine metric and SAE sizes on the same engine or whatever you are working on, it probably is all metric... JMHO!

 

[captmello]

Re: SAE or Metric????

I think it is mostly SAE, but I don't know why...I'd pack both and use what fits. I haven't wrenched on mine in a couple years so I can't remember. I know the helmet pin uses 1/4 bolts to remove. Maybe someone will chime in with the absolute facts. Why Volvo would have SAE parts is weird. Imagine the guys working on them overseas, dusting off their SAE tools.

 

[Fun Times]

Re: SAE or Metric????

I'm in the both are used in various places category. That seems to be the most common with just about anything worked on to date.

 

[gm280]

Re: SAE or Metric????

The only way to know for sure is when you take off any bolt or nut, actually measure the tread pitch and verify. Like I previously stated, if some seem SAE and you come across a true metric, they are probably all metric that the SAE wrenches manage to work on... It would be extremely expensive to manufacture anything using both SAE and Metric hardware. Think about the tooling a company would have to provide and the taps and die tooling needed to machine... I don't see that happening myself!

 

[RickyGee]

Re: SAE or Metric????

Thanks for all the responses. I have full SAE and Metric tools, so I'm mostly concerned with internal threads, like on the helmet plug and the hinge pins. The helmet plug is said to be M8 in the manual, but several forum threads have talked about using SAE bolts to jack it out. Same with the hinge pins. And I read that the 4 allen head bolts holding the double bearing box cover on are SAE threads. Same with the oil plugs. I wish I could get to my drives, but until I pull the stern out of the water, the only way is with a mask and wetsuit...and the water is only 50 degrees right now... It makes no sense to me that a Swedish drive manufacturer would use SAE threads on the drive, even though the engine is mostly SAE. But I used to own a 1994 Chevy Astro and it used whatever, wherever...drove me nuts.

 

[gm280]

Re: SAE or Metric????

Thanks for all the responses. I have full SAE and Metric tools, so I'm mostly concerned with internal threads, like on the helmet plug and the hinge pins. The helmet plug is said to be M8 in the manual, but several forum threads have talked about using SAE bolts to jack it out. Same with the hinge pins. And I read that the 4 allen head bolts holding the double bearing box cover on are SAE threads. Same with the oil plugs. I wish I could get to my drives, but until I pull the stern out of the water, the only way is with a mask and wetsuit...and the water is only 50 degrees right now... It makes no sense to me that a Swedish drive manufacturer would use SAE threads on the drive, even though the engine is mostly SAE. But I used to own a 1994 Chevy Astro and it used whatever, wherever...drove me nuts.

I can understand products that use subassemblies in their marketable finished product to sell to the public using different SAE and Metric size hardware. Like you stated your 1994 Chevy Astro had whatever everywhere. Since not all of that vehicle was designed at one place I can see the transmissions using one type hardware while the engine of another. But what I have an issue with is a subassemblies using both types in their design from the same manufacturing plant. The Engineering side of me sees no reason to do such a thing myself. There is no advantage using one over the other. There are equal capabilities from SAE and Metric hardware to cover any need for the holding capabilities and power and torque specs. So I simply can't see a design engineer crossing over in his design....but that is just my design opinion...

 

[skinnydip]

Re: SAE or Metric????

I'm pretty sure when I removed the oil vent it took a SAE allen drive. I was pretty surprised at that. I'm positive it took a metric flathead screwdriver to drain the oil.

 

[RickyGee]

Re: SAE or Metric????

I'm pretty sure when I removed the oil vent it took a SAE allen drive. I was pretty surprised at that. I'm positive it took a metric flathead screwdriver to drain the oil.

Dang! I'm going to have to get one of those! :laugh: I've lost my left handed crescent wrench too! This project may be doooomed....
Seriously, I'm interested in threads, not heads. For instance, I have to make (adapt) my pressure testing tools to fit the openings with no chance of galling the threads, or leaking. So it would be nice to know what the thread pitch is (like M8x1.25? M10x1.5? or 5/16-24, etc.) so that I can get the necessary adaptors. I have no access to my drives so I can't check them myself or I would. The shop manual is useless for this, so I'm at the mercy of good folks who have been there before, and kind enough to share their wisdom. Thanks heaps.

 

[captmello]

Re: SAE or Metric????

When I change the fluid in my outdrive, I use a standard store bought pump to fill my outdrive from the bottom. The same pump fits my johnson outboard lower unit. I don't know the thread size, but it must be a stsndard size.

like this:

Lower Unit Pump Fluid, 32 oz. Quart Bottle - LubriMatic 55005

looks like 3/8-16

 

[RickyGee]

Re: SAE or Metric????

Great tip, Capt' THANKS! Kills 2 birds with one stone, and proves pretty solidly that VP used SAE in at least ONE location. I can use the metal adator with that pump for the pressure test, then use the pump to refill. It also reminded me that I got rid of my other lower unit pump when I sold my SeaRay, and I'm going to need to get another anyway. Love this forum...:joyous:

 

[RickyGee]

I can now say postively that a 1991 DP-C drive is nearly all SAE, surprisingly. The only metric threads on the exterior are the support fork pins (M18) and the prop cone nut lock bolt internal threads on the aft prop shaft. By the way, the Volvo shop manual is WRONG... the jacking bolts for the helmet plug are 1/4-20, NOT M6. There is also an error in the VP IPC...The prop cone lock bolt is NOT M12 (872546)... it's